나노초 펄스 파이버 레이저를 이용한 탄소섬유강화플라스틱의 미세 구멍 어레이 레이저 드릴링

정도관(Do Kwan Chung) 한국기계가공학회 2024 한국기계가공학회지 Vol.23 No.5

Micro-hole array processing using laser irradiation off-time control was studied to obtain excellent machining shape without thermal damage during laser drilling of CFRP. When continuous micro-holes are machined, closer hole spacings worsen the machined shape owing to thermal damage. For a microhole, a single point is repeatedly irradiated with a laser. The laser irradiation off-time control method sets the laser off time for a set of irradiations, which suppresses heat accumulation and prevents thermal damage. This technique was used to process a micro-hole array with a hole spacing of 0.3 mm without thermal damage. Furthermore, the laser off-time was applied to the laser scanning method, which has a laser off-time for each set of laser scans, and a micro-hole array with a hole spacing of 0.14 mm was fabricated without thermal damage. For small hole spacings, the laser scanning method using the laser off-time yielded better machining results than the laser irradiation off-time control. The laser scanning method was unsuitable for this experimental setup when the hole spacing exceeded 0.4 mm. The laser irradiation off-time control method was suitable for large hole spacing.

Higher-level Production of Ascomycin (FK520) by Streptomyces hygroscopicus var. Ascomyceticus Irradiated by Femtosecond Laser

Hai-shan Qi,Xing Xin,Shan-shan Li,Jian-ping Wen,Yun-lin Chen,Xiao-qiang Jia 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4

Femtosecond laser irradiation technology was employed for the first time to improve the ascomycin (FK520)yield of Streptomyces hygroscopicus var. ascomyceticus NT2-11, which is an N-methyl-N-nitro-N-nitrosoguanidine (NTG)-induced strain derived from S. hygroscopicus (ATCC14891). The mutant FS35 with high and stable FK520 production capacity was then obtained in the optimal irradiation conditions (25 mW for 6 min) by the Titanium sapphire laser system (810 nm, 76 MHz, 150 fs). The FK520 production capacity of FS35 was 45% higher than that of the parental strain NT2-11. Moreover, under the optimal fermentation conditions, FK520 fermentation titer of FS35 reached 300 mg/L and the intrinsic kinetics of FS35 and NT2-11 were investigated comparatively in 3phases. The mathematical models provided a good description of FK520 fermentation process for both strains and valuable information for optimizing operation and pilotplant enlargement research. The comparative studies on parameters of the models confirmed the advantages in production and the decrease of substrate inhibition through femtosecond laser irradiation. Therefore, femtosecond laser irradiation provides a promising way to enhance the production of FK520 in S. hygroscopicus. Femtosecond laser irradiation technology was employed for the first time to improve the ascomycin (FK520)yield of Streptomyces hygroscopicus var. ascomyceticus NT2-11, which is an N-methyl-N-nitro-N-nitrosoguanidine (NTG)-induced strain derived from S. hygroscopicus (ATCC14891). The mutant FS35 with high and stable FK520 production capacity was then obtained in the optimal irradiation conditions (25 mW for 6 min) by the Titanium sapphire laser system (810 nm, 76 MHz, 150 fs). The FK520 production capacity of FS35 was 45% higher than that of the parental strain NT2-11. Moreover, under the optimal fermentation conditions, FK520 fermentation titer of FS35 reached 300 mg/L and the intrinsic kinetics of FS35 and NT2-11 were investigated comparatively in 3phases. The mathematical models provided a good description of FK520 fermentation process for both strains and valuable information for optimizing operation and pilotplant enlargement research. The comparative studies on parameters of the models confirmed the advantages in production and the decrease of substrate inhibition through femtosecond laser irradiation. Therefore, femtosecond laser irradiation provides a promising way to enhance the production of FK520 in S. hygroscopicus.

Comparison of Electronic-Excitation-Induced Structural Modification of Carbon-Based Nanomaterials with that of Semiconductor Surfaces

Noriaki Itoh,Chihiro Itoh,Junichi Kanasaki 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.6

Modification by electronic excitation of semiconductor surfaces and carbon-related quasi-twodimensional (2D) nanostructured materials, namely graphene, carbon nanotubes is reviewed. Defect creation in these materials takes place not by low-intensity photoirradiation, but by laser or electron irradiation. The defect creation processes are different from ordinary photochemical processes in molecules or in some solids like alkali halides, which can be modified by a localized exciton. It is pointed out that there are common features in defect creation by electronic excitation in semiconductor surfaces and carbon-related quasi-2D nanomaterials: the yield-intensity relation shows strong superlinearity for laser irradiation near the bandgap energies and linearity or weak superlinearity for higher energy electron or photon irradiation. These results are explained in terms of multi-hole localization, in which bonds are weakened more strongly and more energy is available upon recombination with trapped electrons in comparison with excitons. The multi-hole localized state is considered to be realized by the creation of dense excitons or by cascade excitation for laser irradiation and by multiple excitations or multiple exciton generation by single impacts for electron irradiation. The review includes also polymerization of C60 films by electronic excitation, which is induced by low-intensity photoirradiation as well as by laser or electron irradiation. The experimental observation that laser or electron irradiation polymerize C60 films differently from low-intensity photoirradiation is explained in terms of multi-hole localization similar to the defect formation mechanism. Although fragmentation of C60 is due to electronic excitation of the molecule, it is included in the review because its yield is strongly superlinear for laser irradiation near bandgap energies and weakly superlinear for high-energy electron or photon irradiation as for other cases.

Direct-laser-patterned friction layer for the output enhancement of a triboelectric nanogenerator

Kim, Daewon,Tcho, Il-Woong,Jin, Ik Kyeong,Park, Sang-Jae,Jeon, Seung-Bae,Kim, Weon-Guk,Cho, Han-Saem,Lee, Heung-Soon,Jeoung, Sae Chae,Choi, Yang-Kyu Elsevier 2017 Nano energy Vol.35 No.-

<P><B>Abstract</B></P> <P>Among the many types of wasted energy around us, mechanical energy has been considered to have a considerable amount of potential to be scavenged due to its abundance and ubiquity in our lives. To convert ambient mechanical energy into electrical energy efficiently, the triboelectric nanogenerator (TENG) has been intensively studied. Polydimethylsiloxane (PDMS), due to its superior mechanical and electrical properties, has commonly been selected as a friction layer in TENGs. Herein, it is newly discovered that the output power of a fabricated TENG is highly correlated with the Young's modulus of PDMS. An enhancement of the output power is achieved by the optimization of the PDMS mixture ratio. In addition, to improve the output power of the TENG further, a well-ordered microstructure was directly created on the surface of the PDMS by means of ultrafast laser irradiation. Direct patterning to create the surface morphology on the PDMS surface with the aid of laser irradiation is more efficient than conventional surface modification techniques such as replication and a few microfabrication steps. Compared to a control TENG using bare PDMS, an increase in the output power of more than twofold is achieved by an experimental TENG using patterned PDMS with a laser power of 29mW. The TENG utilizing the patterned PDMS achieves a maximum output power density level of 107.3μW/cm<SUP>2</SUP>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Direct-laser-patterned polydimethylsiloxane (PDMS) is utilized as a triboelectric dielectric layer. </LI> <LI> Correlation between the Young's modulus of the PDMS and the corresponding electrical performance of the TENG is discovered. </LI> <LI> Optimal condition of laser power for maximum electrical output power is experimentally analyzed. </LI> <LI> By using femtosecond laser irradiation, micro/nanostructures are directly patterned on an appropriately prepared PDMS. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Control of Laser-induced Mechanical Effects by Using a Dual-wavelength Irradiation Method

백준혁,양승진,김재영,장경민,박종락,염동일,김지선,김형식,전재훈,정순철 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.12

A straightforward method of controlling laser-induced mechanical effects in biological tissues is to regulate the pulse energy of the irradiating laser. Because the local temperature of the irradiated region rises as the laser’s pulse energy increases, this method cannot independently control purely mechanical effects without changing the thermal effects. Here, a dual-wavelength irradiation method is proposed in which biological tissues are irradiated simultaneously by using two laser pulses with different wavelengths, and laser-induced mechanical effects are continuously controlled with no change in the maximum temperature increase by systematically varying the energy of each laser pulse. The proposed method is analyzed, and its feasibility is demonstrated through numerical simulations.

침습, 비침습 혈관레이저에 의한 고콜레스테롤혈증의 치료 효과 환자 유형별 비교

권미정,김민규,허성웅,윤현민,김원일,권정남,김영균,Kwon, Mi-Jung,Kim, Min-Kyu,Heo, Sung-Woong,Youn, Hyoun-Min,Kim, Won-Il,Kwon, Jung-Nam,Kim, Young-Kyun 대한약침학회 2006 Journal of pharmacopuncture Vol.9 No.2

Objective : The purpose of this study was to compare and analyze the effect of ILIT and ELIT according to sex, age, disease on Hypercholesterolemia. Methods : The 73 patients who were irradiated to the Intravascular Laser and the 57 patients who were irradiated to the Extravascular Laser from 1999 to 2005 in Sam-se oriental medicine hospital were the study group. They were irradiated two or three times a week and checked total cholesterol before and after ten times of irradiation. The checked total cholesterol point, 150-199 were normal, 200-239 were borderline, over 240 were abnormal. They were classified into male and female(43 persons, 87 persons), adult and 01d(62 persons, 68 persons), cardiovascular disease and the other diseases(70 persons, 60 persons). Results : 1. Male, adult, and the other diseases groups were more effective in cholesterol reduction and in convertible change of each group than female, old, and cardiovascular disease groups, but only the convertible change of each group had statistic significance. 2. In male, old, and cardiovascular disease, ELIT was more effective than ILIT in cholesterol reduction and convertible change of each group, but this result didn't have statistic significance. 3. In female, ELIT was more effective than ILIT in cholesterol change but this result didn't have statistic significance. ILIT was more effective than ELIT in convertible change of each group and this result had statistic significance. 4. In adult and the other diseases, ILIT was more effective in cholesterol reduction, but this result didn't have statistic significance. ILIT was more effective than ELIT in convertible change of each group too and this result had statistic significance. Conclusion: It was thought to be undesirable to decide which is more effective treatment, but to be more desirable to choose one of ILIT or ELIT according to sex, age, disease than to decide it indiscriminately.

뇌경색(腦硬塞)에 대(對)한 He-Ne laser 정맥혈관내(靜脈血管內) 조사(照射)의 효과(效果)

박양춘,안탁원,김동희,김병탁,Park, Yang Chun,Ann, Taek Won,Kim, Dong Hee,Kim, Byeong Tak 대전대학교 한의학연구소 2000 혜화의학회지 Vol.9 No.1

연구배경(硏究背景): He-Ne laser 정맥혈관내(靜脈血管內) 조사(照射) (Intravascular Laser Irradiation of Blood : ILIB)가 말초(末梢) 및 뇌혈관순환장애(腦血管循環障碍), 뇌기능장애(腦機能障碍), 동맥경화(動脈硬化) 등의 예방(豫防)과 치료(治療) 목적(目的)으로 사용(使用)되고 있으나 이에 대한 한의학(韓醫學)에서의 연구(硏究)는 찾아보기 힘들다. 이에 저자(著者)는 발병(發病) 48시간(時間) 이내(以內)에 내원(來院)하여 뇌전산화단층촬영(腦電算化斷層撮影)으로 진단(診斷)된 초기(初期) 뇌경색(腦梗塞) 환자(患者)에서 ILIB의 효과(效果)를 평가(評價)하고자 본(本) 연구(硏究)를 시행(施行)하였다. 아울러 흰쥐의 국소(局所) 뇌허혈(腦虛血)에 미치는 영향(影響)을 측정(測定)하였다. 방법(方法) : 대상(對象) 환자(患者) 40명(名)을 UC-SHJGS(우황청심환(牛黃淸心丸)-성향정기산(星香正氣散))만을 투여(投與)한 대조군(對照群)과 UC-SHJGS 투여(投與)와 ILIB를 병용(倂用)한 치료군(治療群)으로 나누어 시행(施行)하였다. 대상환자(對象患者)는 모두 변증(辨證)과 무관(無關)하게 UC, SHJGS만을 투여(投與)하고 침치료(鍼治療)는 중풍칠처혈(中風七處穴)로 한정(限定)하였으며 5일간(日間)의 치료기간(治療期間) 동안 치료군(治療群)에서는 출력(出力) 1.8-2.5mW의 He-Ne laser를 1일(日) 1회(回) 50분(分) 동안 조사(照射)하였다. 동물실험(動物實驗)은 흰쥐를 대상(對象)으로 중대뇌동맥(中大腦動脈)을 결찰(結紮)하여 국소(局所) 뇌허혈(腦虛血)을 유발(誘發)하고 대조군(對照群)과 ILIB를 실시(實施)한 실험군(實驗群)으로 나누어 그 허혈면적(虛血面積)과 부종율(浮腫率)을 측정(測定)하였다. 결과(結果) : 1. 증상호전지수(症狀好轉指數)는 대조군(對照群)과 치료군(治療群) 사이에 유의(有意)한 차이(差異)가 없었다. 2. 치료전후(治療前後) 측정(測定)한 내경동맥(內頸動脈) siphon부(部)의 혈관반응성(血管反應性)은 대조군(對照群)과 치료군(治療群)에서 모두 유의성(有意性)있는 변화(變化)가 없었다. 3. 치료전후(治療前後) 측정(測定)한 요골동맥(橈骨動脈)의 혈관반응성(血管反應性)은 대조군(對照群)과 치료군(治療群)에서 모두 유의성(有意性) 있는 변화(變化)가 없었다. 4. 치료전후(治療前後) 측정(測定)한 PT, a-PTT은 대조군(對照群)과 치료군(治療群)에서 모두 유의성(有意性)있는 변화(變化)가 없었고, fibrinogen은 치료군(治療群)에서 치료전(治療前)보다 유의성(有意性) 있게 증가(增加)하였으나 평균값이 정상(正常) 범위(範圍)에서 벗어나지 않았다. 5. 국소(局所) 뇌허혈(腦虛血) 동물(動物) 실험(實驗)에서는 실험군(實驗群)에서 신경학적(神經學的) 결손(缺損), 허혈(虛血) 면적율(面積率), 부종율(浮腫率)이 유의성(有意性)있게 감소(減少)하였다 결론(結論) : 이상(以上)의 연구(硏究) 결과(結果) 뇌경한(腦硬寒)의 초기(初期) 치료(治療)에서 기존(旣存)의 한의학(韓醫學) 치료(治療)에 ILIB를 추가(追加)하는 것이 치료(治療) 효과(效果)를 증가(增加)시킨다는 증거(證據)는 없었으며 동물(動物) 실험(實驗)에서는 뇌경색(腦梗塞)의 치료(治療)에 응용(應用)할 수 있는 가능성(可能性)을 보여주고 있으나 그 효과(效果)와 적응증(適應症)을 구체적(具體的)으로 증명(證明)하기 위한 체계적(體系的)이고 다양(多樣)한 임상실험(臨床實驗)이 지적(持績)되어야할 것으로 생각된다. Background : Intravascular Laser Irrardiation of Blood(ILIB) is used in disorder of cerebral and peripheral blood circulation, dysfunction of brain, atherosclerosis etc., but there are little study about ILIB in oriental medicine. We wished to assess the efficacy of ILIB for the treatment of cerebral infarction. Method : The study group comprised 40 patients who arrived at hospital during 48 hours after attack. All patient were divided into two group. The control group was treated with Uhuangcheongsimhuan(牛黃淸心丸), Seonghyangjeonggisan(星香正氣散), acupuncture therapy only, while the ILIB group was treated with above therapy plus 5 days of irradiation of He-Ne Laser(1.8~2.5mW, 50min. per day). In rat model of middle cerebral artery(MCA) occlusion, the control group was not treated, while the ILIB group was treated with irradiation of He-Ne Laser(1.8~2.5mW, 24sec.). Result : 1. Symptom improve scores did not showed significant difference between control and ILIB group. 2. Vasoreactivity of carotid siphon did not showed significant difference between control and ILIB group. 3. Vasoreactivity of radial artery did not showed significant difference between control and ILIB group. 4. PT a-PTT did not showed significant changes between before and after treatment in both group. Fibrinogen significantly increased after treatment in ILIB group(p<0.05)), but it was in normal degree. 5. ILIB showed a significant decrease of brain ischemic area and edema in rat model of middle cerebral artery(MCA) occlusion. Conclusion : These findings suggest that additional treatment of ILIB is not more useful than traditional therapy only in acute cerebral infarction. But ILIB showed potential effect in rat model of MCA occlusion. So further investigation will be necessary.

Antimonene prepared by laser irradiation applied for nonlinear optical limiting

Weili Shen,Jinning Hu,Teng Ma,Jiaxin Wang,Yi Wei,Yuanzhou Zhang,Jinqiang Wu,Jun Chen 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.6

Antimonene, a novel two-dimension (2D) Group-VA material, shows excellent electrical and optical properties. In this work,antimonene nanosheets or nanoparticles were obtained by laser irradiating antimony powder in isopropanol solution anddiff erent morphology of antimonene were obtained by adjusting diff erent laser irradiation parameters, including irradiationtime and irradiation energy. The nonlinear absorption properties of antimonene with diff erent morphologies under 532 nmnanosecond laser were studied by Z-scan technology. It was found that the reverse-saturation absorption ability was thestrongest when the morphology of the sample was nanosheets, which was very suitable for optical limiting. In addition, dueto the limitation of the application of the sample in the form of solution, we added it into organosilicon, and obtained thesolid antimonene-organosilicon composite with optical limiting function. The results showed that antimonene nanosheetswith best optical limiting ability can be prepared by adjusting the laser irradiation parameters, and the products are successfullyadded into solid matrix to enhance its practicability in protecting people’s eyes and optical equipment from damagecaused by high power laser.

Annealing and laser irradiation effects on optical constants of Ga_15Se_85 and Ga_15Se_83In_2 chalcogenide thin films

A.A. Al-Ghamdi,Shamshad A. Khan,S. Al-Heniti,F.A. Al-Agel,M. Zulfequar 한국물리학회 2011 Current Applied Physics Vol.11 No.3

Chalcogenide thin films finds extensive applications in optical imaging, optical recording, integrated optics, optical communications and microelectronics. Optical constants (absorption coefficient, refractive index and extinction coefficient) of amorphous, thermally annealed and laser irradiated Ga_15Se_85 and Ga_15Se_83In_2 thin films deposited by thermal evaporation onto chemically cleaned glass substrate, were calculated from absorbance and reflectance spectra as a function of photon energy in the wavelength region 400―900 nm. Analysis of the optical absorption data shows that the rule of non-direct transitions predominates. It has been found that the absorption coefficient increasing with increasing the exposure time of laser irradiation and also by increasing photon energy. The optical band gap decreases with increasing annealing temperatures. The refractive index (n) decreases, while the extinction coefficient (k)increases with increasing annealing temperature. The laser irradiated thin films showed a decrease in optical band gap and absorption coefficient with increasing exposure time of laser irradiation. The values of refractive index (n) increases and extinction coefficient (k) decreases with increasing exposure time of laser irradiation. The results have been analyzed on the bases of thermal annealing and laser irradiation effects in the chalcogenide thin films.

Er:YAG 레이저로 처리한 상아질에 대한단일 단계 접착시스템의 결합

이명구 ( Myung Goo Lee ),조영곤 ( Young Gon Cho ) 조선대학교 치의학연구원 2013 Oral Biology Research (Oral Biol Res) Vol.37 No.1

The purpose of this study was to evaluate the influence of Er:YAG laser irradiation on the microshear bond strength (μSBS) of three single-step adhesive systems to dentin. Materials and Methods: The occlusal dentin surfaces of 30 extracted teeth were exposed. Samples were divided into six groups according to laser irradiation of dentin surface and type of single-step adhesive system (LP group: Adper Prompt L-Pop (3M ESPE Dental Products), LP-L group: Er:YAG laser (KEY Laser 3, KaVo)+Adper Prompt L-Pop, GB group: G-Bond (GC Corporation), GB-L group: Er:YAG laser+G-Bond, AB group: ALL-Bond SE (Bisco Inc.), AB-L group: Er:YAG laser+ALL-Bond SE). The bonded specimens were subjected to μSBS test, and the resin-dentin interfaces were observed under field emission scanning electron microscope. Results: There were no significant differences among the μSBS of LP, GB, and AB groups, whereas the μSBS of the LP-L and AB-L groups were significantly higher than that of the GB-L group (p<0.05). More adhesive failures were seen in the laser-irradiated groups than in the non-irradiated groups. All other groups, except the GB-L group, showed close adaptation at the interface of dentin and composite resin. Conclusion: Use of Er:YAG laser irradiation can reduce the bonding strength of composite resin to dentin depending on the type of single-step adhesive system.